A dustproof door is provided at a cassette insertion aperture of a tape player to protect the interior of the tape player against dust or other foreign substances.
One of several existing prior art dustproof door mechanisms for use in a cassette tape player is shown in FIG. 4, in which the mechanism includes a shaft 21 supported at an upper portion of a cassette insertion aperture, a stopper 22 provided at a lower portion of the aperture and a dustproof door 23 pivotably supported by the shaft 21 and biased by a spring (not shown) from the interior of the aperture toward the stopper 22.
When a cassette C is inserted through the aperture, the dustproof door 23 is engaged by an end of the cassette C and rotated thereby in the cassette insertion direction. After the cassette C is fully inserted and dropped onto a reel base 24, the dustproof door 23 is engaged by the other end of the cassette C and maintained in a semi-opened configuration. When the cassette C is ejected, the dustproof door 23 is rotated upwardly by the cassette C (which is elevated from the reel base 24) into a position to allow the cassette C to move outwardly from the interior of the tape player.
Obviously, the prior art dustproof door mechanism in which the dustproof door 23 is maintained in a semi-opened configuration while the cassette C is held in the tape player cannot fully protect the interior against dust or other foreign substances
A countermeasure against this problem will be an arrangement of inserting the cassette C more deeply in the tape player up to a position allowing the dustproof door 23 to rotate back to its closing position. In this case, however, the cassette C itself, when elevated for ejection, cannot rotate the dustproof door 23 to its open position, and rather urges same to the stopper 22. In this configuration, the door will never be opened.